ship.py

import pygame
from pygame.sprite import Sprite

class Ship(Sprite):
    """
    A class to manage the ship
    """
    def __init__(self, ai_game):
        """
        Initialize the ship and set it starting position
        """
        super().__init__()
        self.screen = ai_game.screen
        self.settings = ai_game.settings
        self.screen_rect = ai_game.screen.get_rect()
        
        # load the ship image and get its rect
        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        
        # start each new ship at the bottom center of screen
        self.rect.midbottom = self.screen_rect.midbottom
        
        # Store a float for the ship's exact horizontal position
        self.x = float(self.rect.x)
        
        # Movement flag; start with a ship that's not moving.
        self.moving_right = False
        self.moving_left = False
    
    def update(self):
        """
        Update the ship position based on the moving flag
        """
        # Update the ships x value, not the rect
        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.x += self.settings.ship_speed
        if self.moving_left and self.rect.left > 0:
            self.x -= self.settings.ship_speed
        
        # Update rect object from x
        self.rect.x = self.x
    
    def blitme(self):
        """
        draw the ship at its current location
        """
        self.screen.blit(self.image, self.rect)
    
    def center_ship(self):
        """Center the ship on the screen."""
        self.rect.midbottom = self.screen_rect.midbottom
        self.x = float(self.rect.x)